Improved steam-gage



UNITED STATES PATENT OFFICE.

THOMAS SIIAVV, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO HMSELF AND PHILIP F. JUSTICE.

Specification forming part o'f Letters Patent No. 37,794, dat-ed February 24, 1863.

To all whom in may concern.-

Be it known that I, THOMAS SHAW, of the city an d county of Philadelphia, Pennsylvania, have invented anew and Improved Mode of Constructing Steam-Gages; and I hereby declare the following to be a full, clear, and exact description ot the same, reference being had to the accompanying drawings, and to the letters of reference marked thereon.

The nature of my invention consists in the employment of mercury in a manner as hercjnafter described.

In order to enable others to use and practice my inventioml -will proceed to describe its construction and operation.

On reference to the accompanying drawing, which forms a part of the speeificatiom) which represents a vertical section through the center of the gage, F is a disk, ofcast-iron or other suitable material, having on its under side a recess, on, for the insertion of mercury, as hereinul'ter described.

J is a cylindrical metallic ring firmly secured between disks I and F by means of screws r r.

n n is a disk, of india-rubber, clamped between ring .I and disk F for the purpose as hereinafter described; lV, a disk, of rubber, clamped between pipes K by means of screws P P, said screws uniting the whole firmly to disk I, for the purpose as hereinafter described. Y

O is a screw'for the admission of a steampipe.

-H is a disk, the upper and larger end of which fits loosely in ring J and presses against rubber disk an. The lower end of4 said disk II plays loosely `in pipe K, and resting upon rubber disk W. Said disks (El) downward movement is limited by resting upon the up' per end of pipe K.

The chamber or recess m is filled with mercury for the purposens hereinafter described.

O is a glass tube the bore of which is connected with chamber m by means of an aperture through the center of disk F on a line with said glass tube.

E is a boss, to prevent any lateral motion of glass tube.

X is a piece of rubber intervening between glass tube and disk F, for the purpose of makingr a tiglitjoint between said disk and glass tube, and for the further purpose of compensating for any unequal expansion between the metal and glass.

B is a brass tube for the vsupporting and protect-ion of glass tube. Said tubo l5 has a slot down the center of the front for the purpose of viewing said glass tube.A Upon the edge of said slot aregures indicatingthe pounds pressure per square inch. Said tube is united to disk F by means of a ring. G, extendingr from the periphery of the lower edge of pipe B, through whichpass screws s s into disk F. The upper end of said pipe B has a female screw, through which passes screw D, screwing firmly down upon glass tube C for the purpose of making a tightjoint atn is a female screw through the center of D, for the purpose of inserting a screw with a piece ot rubber on end, in order to close the aperture in tube C, that the same may be transported with mercury in it without the risk of spilling the same. There isan aperture leading into chamber m from the periphery of disk F, for the purpose of inserting the mercury. Said aperture is closed by means of a screw. The whole of which apparatus is united by means' of screws and projections U a u to the board A.

The apparatus is operated in this wise: The steam on being admitted into chamber K presses forcibly upon the lower end of disk H, which force raises disk H, contracting the chamber m, forcing the-mercury up the glass tube O in proportion to the amount of pressure in chamber K. As many times-asthe areaV of the lower end of disk H is less than the larger areaof the ,upper end of disk H, so many times will the pressure per square inch be lighter in chamber m than the pressure of steam in chamber K, which renders practicable the employment ofV a short column of mercury without any other opposing medium for the measurement of high pressures. The object of the rubber disks N and W areto prevent leakage. The movement of disk H being slight, (onehundredth of an inch',) to send the column of mercury tothe top of the tube there is little or nofriction attending the same.

that I claim, and desire to secure by Letters Patent, isv An apparatus when arranged substantially as set forth. and for the purpose specified.

THOMAS SHAW.

Vitiiesses Eems J. SHAW, C. BRAZER. 

